A method and a system for detecting critical driving situations of lorries or passenger vehicles serves in particular in the manner described below to prevent (rear-end) collisions between the own vehicle and a vehicle in front. This method can work without involving a predetermined emergency braking deceleration.
The printed publication DE 41 01 759 A1, and corresponding U.S. Pat. No. 5,278,764 A, both of which are incorporated herein by reference in entirety, show an automatic vehicle brake system with a velocity sensor for establishing the vehicle velocity and a distance sensor for establishing the distance between the vehicle and a vehicle in front. On the basis of the relative velocity and the distance from the vehicle in front, the brake system determines a limit time that is required until the vehicle collides with the vehicle in front, in order to give the driver of the vehicle an alarm signal by actuation of an alarm device if the limit time becomes shorter than a limit time threshold value if the brake pedal is not depressed. If the driver of the vehicle does not depress the brake pedal on delivery of the alarm signal, then following the expiry of a time interval, an automatic braking process is executed to reduce the vehicle velocity to prevent a collision with the vehicle in front to the extent that the limit time is once again greater than the limit time threshold value.
If the limit time threshold value is too short, it is not always possible to avoid colliding with the vehicle in front in the automatic braking process. Exclusive consideration of the limit time up to collision is not sufficient, to be precise. A required overall stopping distance of the vehicle is determined in addition, therefore, from the vehicle velocity and the friction coefficient between the road surface and the vehicle tyres. If the limit time is greater than the specified limit time threshold value, but the distance between the vehicle and the vehicle in front is smaller than the overall stopping distance determined, then the automatic braking process of the vehicle is likewise executed following delivery of the alarm signal, and to be precise until the distance is once again greater than the currently determined overall stopping distance.
To determine the limit time and the overall stopping distance, driving and/or traffic situations are only registered here in simplified form. In complex traffic situations, a risk of colliding with the vehicle in front is possibly not detected or is incorrectly assessed, therefore. The delivery of the alarm signal and if applicable the automatic braking process can therefore be initiated too early, too late, not at all or unnecessarily.
The printed publication WO 2004 028847 A1, and corresponding U.S. Pat. No. 7,425,043 B2, both of which are incorporated herein by reference in entirety, describe a method and a device for triggering an automatic emergency braking process of a vehicle, especially a heavy goods vehicle, to offer an assistance function for preventing a vehicle from colliding with a vehicle in front or to reduce the accident consequences if a collision is unavoidable. A driver warning is triggered if a specified warning condition is fulfilled. If the warning condition is present, based on the momentary driving situation of the vehicle and a specified emergency braking deceleration, the automatic emergency braking process is to be triggered on expiry of a specified warning time duration to avoid a collision of the vehicle with the vehicle in front. Thus on completion of the automatic emergency braking process, a specified target relative velocity or a target safety distance between the vehicle and the vehicle in front should be attained. The momentary driving situation is obtained in this case from the established acceleration of the vehicle and the established relative acceleration between the vehicle and the vehicle in front. These variables should enable the risk of a collision of the vehicle with the vehicle in front to be detected securely in many complex driving situations.
The specified emergency braking deceleration is one of five cumulative criteria in all here, the presence of which is tested for triggering a driver warning. The automatic emergency braking process is only triggered following the triggering of a driver warning and subsequent expiry of a specified warning time duration. The driver warning is to be triggered when a specified warning condition is fulfilled, included in which are (i) the driving situation of the vehicle that is determined taking the established acceleration of the vehicle into account, (ii) a specified emergency braking deceleration, (iii) a specified target safety distance, and (iv) a specified target relative velocity between the vehicle and the vehicle in front, as target conditions that are to be achieved on completion of the automatic emergency braking process, and (v) the established relative acceleration currently existing between the vehicle and the vehicle in front.
Early detection of critical driving situations by suitable evaluation of a sensor arrangement supplying appropriate raw data makes it possible in a critical situation to emit driver warnings (e.g. acoustic, optical, haptic . . . ) and to precondition the vehicle to support the driver in a critical situation (e.g. influencing of a braking assistant, prefilling of the braking system, . . . ).
DE 44 01 416 A1, and corresponding Great Britain Patent No. 2285876 A, both of which are incorporated herein by reference in entirety, refer to a gradually driving style classification between a steady driving style and a dynamic driving style, in which during driving measurement variables which are indicative of driving styles are sensed by vehicle sensors. At least one driving-style code number is determined by means of at least some of the detected measured values using a respectively associated measurement variable/driving-style characteristic diagram which has been stored in advance. An acceleration code number relating to the acceleration behaviour, a braking code number relating to the braking behaviour and a steering code number relating to the steering behaviour are determined separately by which the input parameters of open-loop or closed-loop control devices of different driving-style-adaptive open-loop or closed-loop control systems of a vehicle are adjustable in the dependency, specifically specified for the respective open-loop or closed-loop control device, of the code numbers.
DE 19 510 910 A1, and corresponding U.S. Pat. No. 5,684,473 A, both of which are incorporated herein by reference in entirety, refer to a measuring apparatus for detecting a distance or a space between vehicles running in the same direction and judging whether or not a predetermined safe distance is kept there between. A related warning system generates an alarm when an actual distance between two vehicles is shorter than the predetermined safe distance. The measuring apparatus has a first means for keeping a “personal space” corresponding to the vehicle speed of a vehicle equipped with the measurement apparatus to detect an accurate and reliable measuring apparatus capable of detecting a safe inter-vehicle distance peculiar to each driver by taking account of individual drivers' senses and physical abilities. The “personal space” is a distance, which is considered as alarming or insufficient by the driver. A second means obtains a free running distance, which the vehicle covers during a response time, based on the response time to the driver's braking operation and a relative speed between a preceding vehicle and the measuring apparatus equipped vehicle/own vehicle. A third means obtains a braking distance on the basis of a depressing strength of a braking pedal in the driver's braking operation and the relative speed. A fourth means obtains a reference distance on the basis of the personal space obtained by the first means, the free running distance obtained by the second means, and the braking distance obtained by the third means. A fifth means decides whether an actual distance between the preceding vehicle and the measuring apparatus equipped vehicle is less than the reference distance obtained by the fourth means.
DE 19 921 238 A1, and corresponding U.S. Pat. No. 6,294,987 B 1, both of which are incorporated herein by reference in entirety, relate to a vehicle safety running control system, which predicts or anticipates the possible decelerations of an obstacle present ahead of the vehicle to conduct contact avoidance control using the predicted decelerations. This system should have the capability to predict or to anticipate, in plural values, possible decelerations generated by an obstacle such as another vehicle running ahead of the subject vehicle. From the predicted decelerations, the obstacle avoidance control should be performed, thereby making the control relatively simple, while enabling the control to be well matched to the driver's expectations.
Therefore, an obstacle present ahead on a course of travel of the subject vehicle is detected. Parameters indicative of motion of the vehicle including at least speed of the vehicle are detected. The condition of the obstacle relative to the vehicle is detected. It will be determined whether at least one of alarming and contact avoidance with the obstacle should be operated. A plurality of decelerations which the obstacle could generate is predicted based on the detected parameters (in particular the detected speed of the vehicle, when the subject vehicle runs under no constant acceleration) and the detected relative condition. Based on at least the predicted decelerations it will be determined whether at least one of alarming and contact avoidance with the obstacle should be operated.
DE 10 2005 014 803 A1 relates to a control of a collision avoiding system to duly warn the driver, if, for instance, the distance between its vehicle and an obstacle becomes too small. Depending on a relative speed between the vehicle and the obstacle, the system calculates a minimum distance between the vehicle and the obstacle within which the vehicle had to stop to avoid collisions. The minimum distance corresponds to a minimum collision avoiding time. In case the minimum collision avoiding time falls below a predetermined threshold value, the system outputs a warning. The system is adaptively designed to distinguish, whether the driver dares a more dynamic way of driving, wherein superfluous warning signals are perceived as disturbing, or whether the drivers prefers a more contemplative way of driving and, hence, prefers an early warning to be able to duly evade the obstacle without a too abrupt change of one or more driving parameters, in case he approaches an obstacle. Based on the reaction of the drive in response to a first warning, the threshold for the generation of the signals is adapted in such a manner that future warning only takes place, in case they are necessary for the individual driver. For this purpose, an obstacle distance between the vehicle and an obstacle is detected by means of a periphery sensor. From the obstacle distance and a relative speed of the vehicle with respect to the obstacle a minimum collision avoiding time is determined. A first warning signal is output, in case the minimum collision avoiding time falls below a first threshold value. A driver's reaction is detected and the first threshold value is adapted based on the duration between the signal and the reaction.
DE 10 2005 054 064 relates to a method for avoiding collision of a vehicle with obstacles located on the lane of the vehicle as well as to a warning device to minimize the frequency of false actuations. To avoid a collision of a vehicle with a potential obstacle located on the lane of the vehicle, an open route of the vehicle is determined by means of detecting the distance between the vehicle and the obstacle; the length of a route covered by the vehicle during a full braking until the vehicle stops is calculated as a braking distance; and a collision warning and/or a brake intervention is initiated based on the determined open route and the calculated braking distance. The calculation of the braking distance is based on the analysis of equations of motion, which in turn are based on the assumption of a time-dependent hypothetic acceleration profile, which approximately represents the time course of the acceleration of the vehicle, which is expected, in case a full braking would be initiated for the present point in time. For this purpose, the acceleration and the acceleration gradient of the vehicle are continuously determined and the hypothetic acceleration profile is defined based on the present acceleration and the present acceleration gradient. The hypothetic acceleration profile could be approximated by means of multiple linear sections.
For calculating the braking distance, a time presumably required for stopping the vehicle is calculated based on a velocity profile corresponding to the hypothetic acceleration profile and a route covered during this time is calculated based on a route length profile corresponding to the hypothetic acceleration profile.
A collision warning or a brake intervention is initiated based on a defined distance threshold, in case the open route is less than the calculated brake distance plus the distance threshold. The distance threshold could be equal to a reaction distance, which corresponds to the length of a route covered by the vehicle during a predetermined driver reaction time, wherein the driver reaction time could be predetermined based on the present state of the accelerator pedal and the brake pedal of the vehicle.
In addition, a collision warning or a brake intervention could only be initiated, in case the vehicle is on reverse drive, the open route is greater than a predetermined threshold, or the driving speed is greater than a predetermined speed threshold. The warning device could be part of a parking assist system for supporting the driver with parking.
DE 10 2006 043 676 relates to a driver assist system (for instance lane-departure-warning-system or collision-warning-system) having a warning function, which alerts the driver to dangerous traffic situations. Using common warning systems of such sort, it is frequently impossible to evaluate the traffic situation by means of the available sensors with the required precision. This quite frequently results in disturbing false warnings. To avoid false warnings, the driving dynamics of the vehicle and the driver's actions or the driver's reactions embodied therein are evaluated as information about the diver's attentiveness. Stronger longitudinal accelerations or lateral accelerations, which are outside a comfort zone, are graded as significant indication for an increased driver's attentiveness, in case they correlate to a dangerous situation detected by the assist system. Fluctuations of the longitudinal accelerations or lateral accelerations, which are outside a comfort zone are graded as high attentiveness of the driver and a warning is suppressed in a situation, in which commonly a warning signal would have been output. In this manner the frequency of false warnings could be significantly reduced and for this reason the acceptance of the warning systems could be increased.
DE 10 2006 046 697 relates to the immediate recognition of dangerous situations within road intersection to warn the concerned road users as soon as there is a risk of conflicts or collisions. Therefore, position data of road users present in the intersection are acquired and evaluated to generate a prognosis of the predicted paths of movement of the road users and to determine based on the prognosis whether conflicts or collisions between the road users impend, for the prevention of which countermeasures are taken. Speed and acceleration data of the road users are factored into the position data. For vehicles, a lane of the vehicle in the intersection is determined based on the position data, wherein turning movements (deutsch: Abbiegebeziehungen) of the vehicle are considered by evaluating, to the extent available, additional data of the vehicle. For each road user, own trajectories are determined and their points of intersections are determined, which represent possible conflict points. In case conflict points exist, countermeasures and in particular a warning of the concerned road user are initiated. The conflict points are calculated in consideration of possible brake actions or acceleration actions of the road users.
EP 1 559 607 A1, and corresponding U.S. Pat. No. 7,259,661 B2, both of which are incorporated herein by reference in entirety, relate to collision warning for a vehicle, which is equipped with a distance sensor, and which is suited to generate a reliable warning signal for the driver, in case it is likely that a remaining distance to the vehicle traveling ahead could not be maintained at the end of an ACC-brake application or after a driver brake application. Therefore, the vehicle-deceleration, which had to be applied by the vehicle after the expiration of a driver reaction time, is continuously calculated in an evaluation device in order that a remaining distance to the vehicle traveling ahead can be maintained. If the absolute value of the calculated deceleration exceeds an assumed vehicle deceleration that can be generated by braking on the part of the driver, a collision warning signal is output. A system limit warning is output, if the absolute value of a deceleration, calculated with a driver reaction of zero, exceeds a deceleration that can be achieved by the ACC.
WO 2002/043029, and corresponding U.S. Pat. No. 7,002,452 B2, both of which are incorporated herein by reference in entirety, relate to the detection of the vehicle running conditions of a vehicle ahead, the detection of the vehicle running conditions of a following vehicle, and the detection of the vehicle distance between the vehicle ahead and the following vehicle. The shortest distance between the following vehicle and the vehicle ahead is predicted based on the detected driving conditions of the vehicle ahead, the detected driving conditions of the following vehicle, and the detected vehicle distance. A proper vehicle distance is determined based on the vehicle distance between the vehicle ahead and the following vehicle. A warning or a braking force is generated, in case the predicted shortest distance is less than the predetermined proper vehicle distance.
A target deceleration necessary for maintaining the proper vehicle distance is determined. The speed and the deceleration of the vehicle ahead and the following vehicle are determined. The shortest distance between the following vehicle and the vehicle ahead is predicted based on the detected speed of the vehicle ahead, the detected deceleration of the vehicle ahead, the detected speed of the following vehicle, and the detected vehicle distance. Braking force is generated to make the detected deceleration of the following vehicle to match the calculated target deceleration, in case the predicted shortest distance becomes less than the predetermined proper vehicle distance.
WO 1999/042347, and corresponding U.S. Pat. No. 6,292,753 B1, both of which are incorporated herein by reference in entirety, relate to a brake controller of a vehicle for avoiding a contact of the vehicle with the object, while the automatic operation of the brake shall not disturb the driver. Therefore, an object existing ahead of the vehicle in the direction of movement of the vehicle is detected. The possibility of a contact of the vehicle with the object is determined from the relative positional relationship between the vehicle and the object. A braking means carries out an automatic braking operation based on the result of the determination. A braking operation conducted by the driver is assisted by means of the braking means, in case the driver's braking will is detected during the automatic braking operation.
The driver's braking will is detected by at least on of depressing a brake pedal by the driver, the operation of returning an accelerator pedal by the driver, and the movement of a foot of the driver toward the brake pedal. Before starting of the automatic braking operation, a warning is output to the driver. Within a predetermined interval after the output of the warning, the driver's braking will is detected by at least one of depressing a brake pedal by the driver, the operation of returning an accelerator pedal by the driver, and the movement of a foot of the driver towards the brake pedal. The braking operation assistance for the driver is to maintain the braking force in the automatic braking operation before detection of the driver's braking will, or to increase the braking force in the automatic braking operation.
Critical situations of heavy goods or passenger vehicles should be detected more securely, the driver warned to this effect and/or the vehicle prepared to support the driver for an emergency braking process. Where possible, erroneous warnings and interventions should not occur.